Inertial energy storage device

ABSTRACT

The invention concerns a device wherein the coil tube ( 12 ) forming the condenser of a first heat pump assembly and the coil ( 13 ) which forms a second assembly are each fixed on vertical grids ( 28, 29 ). Said grids are arranged parallel to each other and are embedded in the concrete block ( 3 ) which forms one of the energy storage units incorporated in the system. The grids consist of concrete iron bars welded together into a network with square and rectangular meshes. The means fixing the tubes at certain intersetions of the grid are clamps of a particular type. The grids, the tubes and the clamps are embedded in the concrete block ( 3 ).

[0001] The present invention concerns in general terms heating and airconditioning systems for premises using renewable energy forms, inparticular by means of heat pumps.

[0002] It has already been proposed in this field to use heataccumulators comprising solid blocks in which there are embedded one ormore circuits formed from metallic tubes through which, when the systemis in service, there runs a heat-transfer fluid which may be liquid orgaseous. Patent application WO 96/28703, for example, describes anaccumulator of this type, one of the particularities of which is that itis made from concrete, a material which has several advantages.

[0003] Recent experiments showed that the storage of heat energy inrigid blocks could have practical advantages which are extremelyremarkable with regard to the rationalisation of the installation works,the cost, the reliability of the service, the efficiency and the servicelife, provided that certain provisions were complied with precisely.

[0004] The aim of the present invention is therefore to provide theadvantages able to be obtained, by producing economically an energyaccumulation device of the inertia type comprising certainparticularities which are the object of the invention and which aredefined in the accompanying claims 1 to 12.

[0005] A description will be given below, by way of example, of anembodiment and a few variants of the device according to the invention,referring to the accompanying drawing, where:

[0006]FIG. 1 is a general schematic view in perspective showing adwelling house equipped with a heating and air conditioning system withan energy accumulation device of the inertia type according to oneembodiment of the invention,

[0007]FIG. 2 is a diagram showing a preferred embodiment of the energyaccumulation device of the inertia type according to the invention,

[0008]FIGS. 3 and 4 are views respectively in transverse section and infront elevation in the direction of the arrow A in FIG. 3, showing ablock with two assemblies formed by a grille and a heat-transfer fluidcircuit, according to the preferred embodiment,

[0009]FIGS. 5 and 6 are views in section similar to FIG. 3 showing twovariant arrangements for the grilles,

[0010]FIG. 7 is a view in front elevation of a circuit mounted on agrille, showing the anchoring of the coil at the points where the barscross, and

[0011]FIG. 8 is a schematic perspective view to a larger scale showingan anchoring flange in place on a pipe and on an intersection of thebars of the carrier grille.

[0012] In FIG. 1, there can be seen a villa 1 equipped with a heatingsystem comprising an energy accumulation device of the inertia type 2comprising four accumulation blocks 3 embedded in the ground close tothe building and means for conducting as required the latent heatcontained in the blocks. The latter are connected, by a set offluid-circuit elements designated overall 4, to a heat generator 5 fromwhich various secondary circuits start, supplying normal ancillaryequipment such as domestic hot water 6, room radiators 7 and underfloorheating circuit 8. The generating unit 5 is symbolised in FIG. 1 by twosuperimposed cubicles. Its structure is specified in the diagram in FIG.2. It is also connected by secondary circuits to a solar panel withwater circuit 9 and to a recuperator 10 for excess heat liable to beproduced by a living room flue.

[0013] It will be understood that this enumeration of auxiliaryequipment is given solely by way of example and in is no way exhausted.As will be seen again later, it also encompasses, for example, the caseof a swimming pool and that of a high-temperature solar furnace. Itshows simply the great variety of applications which can be envisaged inany problem of heating and air conditioning premises. The energyaccumulation device of the inertia type which will be described nowsatisfies, by standard and rational means, each particular case whichmay be predicted.

[0014]FIG. 2 shows the walls of the dwelling house 1 and one of theenergy accumulation blocks 3 of the inertia type. This block is placedin an excavation 11 dug close to the building 1 and filled with earth.It has the form of a prism with a large rectangular base placedhorizontally and a top face narrower than the base and parallel to thelatter. The blocks 3 are made from concrete. Their dimensions will bestandardised: for example 2.5×1.7×0.5/0.3 m. The dimensions of theexcavation 11 and the position of each block in its excavation will bedetermined on a case by case basis according to the quantities of energyto be stored and the duration of the periods of reversal of flows, aswill be seen below.

[0015] The connection between the blocks 3 and the generator unit 5,designated 4 in FIG. 1, is made in fact for each block by manifoldsforming two circuits 12 and 13 each with an inlet 12 a, 13 a and anoutlet 12 b, 13 b. The active parts of the manifolds 12, 13 are embeddedin the concrete of the block 3 and, as from the inlet segments 12 a, 13a, are angled in coils in a layer so that the contact surfaces are aslarge as possible and facilitate heat exchanged between theheat-transfer fluid circulating in the circuits and the concrete.

[0016] The heat-generating unit 5 consists in the embodiment describedof two entirely separate sets of heat pumps 14 and 15. Each setcomprises a complete heat-transfer fluid loop of the phase change typewith: an upstream circuit element and a downstream circuit element,between the two elements a compressor and a pressure reduction valve, onone of the elements a heat exchanger, and a secondary circuit with oneor more radiating components.

[0017] For the assembly 14, the compressor and the pressure reductionvalve are designated 16 and 17, the upstream circuit is the circuit 12,embedded in the block 3 and functioning as a condenser by supplying heatto the block. The downstream circuit is then the evaporator designated18 a, 18 b. The fluid passes into the exchanger 19, absorbing the heatsupplied by the secondary circuit 20 and picked up in the refrigeratingcircuit 21. It will be understood that this assembly can keep a coldroom running or constitute an air conditioner intended to function insummer. It could also fulfil other functions as will be seen below.

[0018] The assembly 15 consists of similar elements but functioning inthe opposite direction. There can be seen in FIG. 2 the pressurereduction valve 22, the compressor 23 and the upstream circuit 24 a, 24b functioning as a condenser and supplying, through the exchanger 25,the heat picked up in the downstream circuit 13 to the secondary circuit26 supplying the radiator 27. The latter corresponds to the element 7 orto the element 8 in FIG. 1. The water heater 6 will also be connected tothe circuit 26.

[0019] Thus in each block 3 there are embedded two circuit elements 12,13 each incorporated in one of the units 14 or 15 in the group 5 andconstituting in one case the condenser 12 of the cold-production unit 14and the other the evaporator 13 of the heat-production unit 15. Thisarrangement gives very great flexibility in the management of the systemdescribed. FIGS. 3 and 4 show once again the block 3 with theheat-transfer fluid circuits 12 and 13 embedded in the concrete. Each ofthese circuits is formed from a segment of tube of sufficient length,angled in a coil. The tubes can be made from stainless steel or copper,with for example a diameter of 10 mm and a wall thickness of 0.5 mm.They can also be produced from synthetic material, for example frompolyethylene, or from composite materials. Each circuit 12, 13 ismounted on a grille 28, 29. This grille can be formed from metallicbars, in particular concrete-reinforcement bars, for example 6 mm indiameter and welded at right angles to one another so as to form alattice with square or rectangular meshes, having for example a sidemeasuring approximately 15 cm. The grille can also be produced fromsynthetic material, for example polyethylene, with welded or bondedbars, or moulded at one go. The grilles 28, 29 constitute supportstructures for the circuit elements, particularly useful fortransporting and installing the circuit before pouring the concrete.Where the accumulator units are prefabricated, use ill preferably bemade of grilles formed from concrete reinforcement bars, the grillesthen also having the function of providing the cohesion of the concrete.The operation of bending the tubes and fitting the coils exactly withrespect to the intersections of the grille may be performed in arational manner by means of a support having the form of a plate havinggrooves in which the bars of the grille are placed. The plate will beequipped with grippers fixing the tube with respect to the support andwith respect to the grille at the location where a bend in the coil mustbe produced. The technique of mounting the coils on the grilles will bereturned to later.

[0020] Although these operations of mounting the coils on the grillescan be performed on the site, in order to allow optimum control of thequality of manufacture and to reduce the working time on site to themaximum possible extent, these operations will preferably be performedin the factory, the grille/coil assemblies being transported to the sitealready assembled, so as to be able to be fitted directly with formwork,or directly inside a trench in the ground, the sides and bottom of thetrench serving as formwork, after which the concrete can be poured. Theinlet and outlet segments 12 a, 12 b, 13 a, 13 b of the circuit elementswill be designed so as to be sufficiently long to allow subsequentconnections. With the dimensions indicated, each grille/coil assemblyhas a weight of 50 to 100 kg, making it easy to handle. The sitetherefore does not require any access means arranged for particularlyheavy machinery. However, if the equipment so permits, the blocks 3 canalso be manufactured entirely in the factory and transported to the siteas products ready for installation.

[0021] As can be seen in FIG. 3, the two grilles 28, 29 are placed in avertical position at a short distance from each other at the centre ofthe block. Each coil circuit 12, 13 is fixed against the grille, whichcarries it on the outside. The grilles and the branches of the coils areoffset in height in one of the assemblies with respect to the other byhalf the pitch of the grille. This arrangement ensures optimum thermaluse of the properties of the concrete and of the iron bars of thegrilles. The latter fulfil the role of thermal bridges and promote thediffusion of heat.

[0022] The blocks can be used as heat reservoirs, either inaccumulation, or in “draining”, that is to say only one of the twocircuits, the condenser circuit 12 or the evaporator circuit 13, is inoperation. However, the functioning sequences can be variable, forexample daily or seasonal. It is therefore possible to conceive of caseswhere the two circuits are functioning at the same time, the energymerely transiting through the block. Such a configuration isparticularly useful for hotels and hospitals, where air conditioning andthe production of domestic hot water simultaneously and continuously arenecessary. The close arrangement of the two assemblies 12-28, 13-29 thenhas the advantage that the differences in temperature are very small.However, in this case, the grilles 28 and 29 will be disposed at asubstantially greater distance from each other than those shown in FIG.3, generally at a distance of between 5 and 10 cm, so as to allow gooddiffusion of the energy around the tube. If the temperature differencebetween the heat source and the heat diffuser is itself small, then thecoefficient of performance (COP) of the sets is particularly high. Thiswill be the case for example when, off season, it is wished to use theheat energy from the water of a swimming pool in order to warm inhabitedrooms, or conversely, when an air-conditioning effect or the picking upof the solar heat by the panel 9 are used to heat the water in theswimming pool. Because the pumps are reversible, the two circuits canalso be used simultaneously, either as an accumulator or for draining.FIGS. 5 and 6 are sections similar to that in FIG. 3 and show twovariants of the arrangement of the assemblies 12/28, 13/29 which, insome cases, result in even better performance than that of thepreferential execution described up till now. In these two figures, thevertical bars of two grilles 28, 29 are situated in the same plane, thehorizontal bars can be placed as close to each other as possible (FIG.5) or, preferably, offset, for example by a half-pitch (FIG. 6).

[0023]FIG. 7 shows the anchoring of the heat-transfer fluid tubes to thegrilles. It shows a view of the assemblies 12/28, 13/29 in the oppositedirection to the arrow A in FIG. 3. A grille portion 29 is depicted inelevation with a portion of a heat-transfer fluid tube 13 bent in acoil. Although only six horizontal branches and four bends at 180° havebeen shown, it is obvious that this number is not determinant and that,in practice, it will be higher. The horizontal branches of the coil 13are fixed to junction points of the grille 9 by fasteners 30 formed bymetallic or synthetic bands such as Colson collars. In the example inFIG. 7, each collar is attached to a junction point on the grille andholds the horizontal branch of the tube 13 against a horizontal bar ofthe grille. FIG. 8 also illustrates the arrangement. According to onevariant, the collars are attached not to a junction point of the grillebut along a horizontal bar of the grille. The number of collars andtheir alternating arrangement on each horizontal branch of the coil willbe chosen on a case by case basis. It should be noted that thisanchoring method provides an elastic pressure of the tubes against thebars of their support grille, which enables the assembly to withstanddifferent grille/tube expansions or contractions during temperaturevariations. Moreover, the angled portions of the tube for making up thecoil can be provided with a device allowing differentiatedexpansion/contraction of the tube with respect to the concrete. Such adevice can be produced for example in the form of sleeves 31 (shownschematically in FIG. 7) made from compressible polyurethane foam(preferably with closed cells) which are disposed around the angledparts of the tube forming the coil.

[0024] The system described is particularly advantageous for severalreasons: it makes it possible to take advantage of the picking up ofenergy coming from ancillary sources, such as a swimming pool or awater-circulation solar panel with a high coefficient of performance(COP), or for example a heat recuperator in a flue or one in ahigh-temperature solar furnace. The accumulation of heat in the blockscan be extended, during seasonal periods, to the surrounding ground,which functions both as an insulator and as a receiver. Thus the watertubes coming from the solar panels could be directly integrated in theblocks 3 or in some of the blocks, which avoids the interposing of aheat exchanger. Finally, it is obvious that the cases where the blocks 3and the surrounding ground directly pick up the ambient heat during thesummer and only the circuits 13 and the set 15 are provided, alsorepresent an application of the present invention.

[0025] Thus the energy accumulation device of the inertia type accordingto the invention can serve equally well as a heat energy accumulator, atemperature equaliser, a temperature exchanger or a temperatureregulator, the whole being reversible.

[0026] The accumulation blocks depicted in FIGS. 1 and 3 have across-section in the shape of a triangular or trapezoidal prism with atop base with a size less than that of the bottom base. However,naturally, the blocks 3 can be produced in any other shape, such as forexample in the shape of a T, so as to prevent the block from sinkinginto the ground, or also rectangular in shape.

[0027] Although the device according to the invention has been describedwith three concrete blocks 3, the said blocks can also be produced fromother solid or semi-solid materials, such as for example with bentoniteor other similar gels.

[0028] A description has not been given here of the means which will beprovided for allowing effective management of the whole of the system,such as valves with several ways for controlling the flows, devices fordraining and, where necessary, cleaning the tubes, and measurement andmonitoring apparatus. These means will naturally be provided accordingto requirements. Although a system has been described with two separatesets of heat pumps functioning one as a heat producer and the other as acold producer, it is also possible to provide only one set.

[0029] In addition, the possible applications of the storage devicedescribed are obviously not limited to the heating and air conditioningof villas, but equally relate to any building where the rooms must bewarmed or cooled.

1. An energy accumulation device of the inertia type, in particular fora heating and/or air conditioning system for premises, comprising atleast one block (3) of solid or semi-solid material, and at least oneheat-transfer fluid circuit (12, 13) embedded in each block,characterised in that at least one grille (28, 29) is embedded in eachblock (3) and in that each of the said circuits consists of a continuouscircuit, curved in a coil, mounted on one of the grilles so as to allowdifferential expansion/contraction of the pipes with respect to thegrille.
 2. A device according to claim 1, characterised in that at leastone circuit is integrated in a heat-transfer fluid loop with phasechange of a heat pump (14, 15).
 3. A device according to claim 1 orclaim 2, characterised in that each block (3) has two assemblies (12,28; 13, 29) of a grille and a circuit, the grilles being plane andplaced parallel in the block.
 4. A device according to claim 1,characterised in that the block (3) has the shape of a polyhedron whosebase is rectangular and placed horizontally and which has a top facewhich is also plane and parallel to the base, the grille or grilles (28,29) being vertical.
 5. A device according to claim 2, in which the twocircuits (12, 13) of a block are integrated in different heat exchangeloops, characterised in that the device is associated with two sets ofheat pumps (14, 15), one of the said circuits functioning as anevaporator and the other as a condenser.
 6. A device according to anyone of the preceding claims, characterised in that the block or blocks(3) are in the shape of a prism with a triangular vertical section.
 7. Adevice according to one of claims 1 to 5, characterised in that theblock or blocks (3) are in a T shape.
 8. A device according to any oneof the preceding claims, characterised in that the material of the blockor blocks is concrete.
 9. A device according to any one of claims 1 to7, characterised in that the material of the block or blocks is a gel.10. A device according to any one of claims 4 to 9, characterised inthat the block or blocks are embedded in the soil, their faces beingdirectly in contact with the ground.
 11. A device according to any oneof the preceding claims, characterised in that a circuit, in at leastone block, is connected to an ancillary heat source without connectionwith a heat pump, the ancillary heat source being a solar panel (9), arecuperator for the heat in a flue (10), a high-temperature solarfurnace, etc.
 12. A device according to one of the preceding claims,characterised in that the grille is formed from metallic bars connectedtogether at junction points.
 13. A device according to one of claims 1to 11, characterised in that the grille is made from synthetic material.14. A device according to one of the preceding claims, characterised inthat the pipes are metallic tubes.
 15. A device according to one ofclaims 1 to 13, characterised in that the pipes are tubes made fromsynthetic material.
 16. A device according to one of the precedingclaims, characterised in that the angled portions of conduit forming thecoil are provided with a device allowing differentialexpansion/contraction of the pipe with respect to the concrete.
 17. Adevice according to claim 16, characterised in that the angled portionsof the conduit are provided with sleeves (31) made from compressiblepolyurethane foam.
 18. An assembly formed by at least one grille andcomprising at least one continuous pipe bent in a coil, anchored to thesaid grille, as part of the device according to one of the precedingclaims.